1. Field of the Invention
The present invention relates to a microprobe used for observing a very small area (on a nanometer order) of a surface of a sample and a scanning type probe apparatus using the microprobe.
2. Description of the Prior Art
Currently, there is known a Scanning Probe Microscope (SPM) as one of the microscopes (scanning type probe apparatus) used for observing a very small area on a nanometer order at a surface of a sample. One type of scanning type probe microscope, an Atomic Force Microscope (AFM), uses a cantilever provided with a stylus at its front end portion as a microprobe, the stylus of the cantilever is scanned along a surface of a sample, and interactive action (an attractive force or repulsive force, or the like) between the surface of the sample and the stylus is detected as an amount of bending of the cantilever to thereby enable one to measure a shape of the surface of the sample.
The bending amount of the cantilever is detected by irradiating a front surface of the cantilever with an irradiation beam such as a laser beam and measuring a reflection angle of a beam reflected from the front surface of the sample. Actually, the reflection angle is provided by using an optical detector of a photodiode or the like divided in two and from an intensity distribution of the beam received at respective detecting portions.
In observing the sample by AFM, generally, there is selected a cantilever having sharp stylus which differs in sharpness in accordance with observation accuracy and observation range and the cantilever is used by being mounted to an apparatus. For example, when a wide area of micrometer order is intended to be measured at a high speed, a cantilever having a stylus with a low sharpness degree is used although the resolution is low (hereinafter, referred to as a cantilever for low resolution), further, when a narrow area of nanometer order is intended to measure with high resolution, there is used a cantilever having a stylus with a high sharpness degree (hereinafter, referred to as a cantilever for high resolution).
In this way, there causes a need of interchanging a cantilever in accordance with an object of observation and the interchange operation becomes a troublesome operation of finely adjusting an irradiation angle of the above-described irradiation beam or a receive angle of an optical detector or the like. Further, before and after the interchanging operation, a position of observation is frequently shifted considerably and it is difficult to carry out accurate sample observation.
Hence, there is proposed a microprobe of a double lever type having both of the cantilever for low resolution and the cantilever for high resolution by making common a support portion thereof. Particularly, according to the double lever type microprobe, in accordance with the object of observation, by switching operation utilizing thermal expansion of a heater, switching of the two kinds of cantilevers is made possible.
FIG. 12 is a perspective view showing a microprobe 1 of the double lever type and a constitution of essential portions of a scanning type prove apparatus using the microprobe 1. Further, FIG. 13 is a side view for explaining operation of the double lever type microprobe 1.
In FIG. 12, the microprobe 1 is arranged above a sample 4 and is fabricated with silicon as a base material and a support portion 1a is formed with a cantilever portion 1b for low resolution and a cantilever portion 1d for high resolution. As shown by FIG. 12, the low resolution cantilever portion 1b and the high resolution cantilever portion 1d are supported by the support portion 1a to project in minus y-axis direction designated in the drawing from an end edge of the support potion 1a and to be spaced apart from each other by an interval 1f. Further, in actual use, the support portion 1a is fixed to a fixing member, not illustrated.
Further, the sample 4 is moved in xy plane and in z-axis direction shown in the drawing by actuators, not illustrated, thereby, scanning over the surface of the sample of the microprobe 1 and proximity control between the microprobe 1 and the surface of the sample are achieved.
Further, the low resolution cantilever portion 1b and the high resolution cantilever portion 1d are formed to bend in z-axis direction shown in the drawing with portions thereof bonded to the support portion 1a as bending portions. Further, a front end portion of the low resolution cantilever portion 1b is formed with a sharpened stylus 1c for low resolution to project in minus z-axis direction.
The low resolution stylus 1c is proximate to a sample surface 4a of the sample 4, a sharpness degree thereof is lower than a sharpness degree of a stylus 1e for high resolution, mentioned later, and a length thereof in z-axis direction is longer than a length of the high resolution stylus 1e. That is, the low resolution stylus 1c (low resolution cantilever portion 1b) is used in measuring a wide area with low resolution.
Meanwhile, a front end portion of the high resolution cantilever portion 1d is formed with the sharpened stylus 1e for high resolution to project in minus z-axis direction. According to the high resolution stylus 1e, the sharpness degree is made higher than the sharpness degree of the low resolution stylus 1c and the length in z-axis direction is made shorter than the length of the low resolution stylus 1c. That is, the high resolution stylus 1e (high resolution cantilever portion 1d) is used in measuring a narrow area with high resolution.
As described above, detection of bending of the low resolution cantilever portion 1b and the high resolution cantilever portion 1d is carried out by measuring reflection beam reflected at surfaces of the cantilevers. Detection of bending of the low resolution cantilever portion 1b is carried out such that irradiation beam La1 irradiated from a light emitting element 51 is reflected and reflection beam Lb1 is received by a light receiving element 61. Further, similarly, detection of bending of the high resolution cantilever portion 1d is carried out such that irradiation beam La2 irradiated from a light emitting element 52 is reflected and reflection beam Lb2 is received by a light receiving element 62.
Further, according to the low resolution cantilever portion 1b, as shown by FIG. 13, there is formed a heater 3 for the above-described switching operation on a surface of a side of the low resolution stylus 1c. Particularly, the heater 3 is formed at a bond portion (bending portion) for bonding the low resolution cantilever portion 1b and the support portion 1a, and is heated by conducting electricity thereto via a wiring, not illustrated, and the low resolution cantilever portion 1b can be bent in z-axis plus direction at the heater 3 portion by thermal expansion of the heater 3 per se or by a difference in thermal expansion of a side of the low resolution cantilever portion 1b formed with the heater 3 and a side thereof opposed thereto.
Here, temperature of the heater 3 before bending the low resolution cantilever portion 1b is designated by notation T0 and temperature of the heater 3 for bending the low resolution cantilever portion 1b (operational temperature) is designated by notation T( greater than T0).
Therefore, according to a scanning type probe apparatus using the microprobe 1, an initial state, that is, a state in which temperature of the heater 3 is T0, is set to a state in which the low resolution stylus 1c having a height higher than that of the high resolution stylus 1e can be used as a state in which the low resolution stylus 1c is more proximate to the sample surface 4a than the high resolution stylus 1e and under the state, observation of a wide area with low resolution can be carried out.
Further, when the low resolution cantilever portion 1b is bent in z-axis plus direction by elevating temperature of the heater 3 to the operational temperature T by flowing current to the heater 3, in this state, there is brought about a state in which the side of the high resolution stylus 1e becomes more proximate to the sample surface 4a than the low resolution stylus 1c and accordingly, observation of a narrow area with high resolution can be carried out.
Hence, according to the above-described double lever type microprobe, the stylus can be switched to an exclusive stylus for carrying out either of observation of a wide area with low resolution and observation of a narrow area with high resolution without executing the interchanging operation of the microprobe.
However, according to the microprobe 1 and a scanning type probe apparatus using thereof, necessarily, there are needed two routes of detecting units of a detecting unit for detecting the bending amount of the low resolution cantilever portion 1b (light emitting element 51 and light receiving element 61) and a detecting unit for detecting the bending amount of the high resolution cantilever portion 1d (light emitting element 52 and light receiving element 62).
Therefore, according to the conventional microprobe 1 and a scanning type probe apparatus using thereof, there poses a problem in which it is necessary for the two detecting units to individually carry out fine adjustment of arrangement positions and angles, further, since the two routes of detecting units are needed, the constitution becomes complicated.
Further, according to the conventional microprobe 1 and a scanning type probe apparatus using thereof, since there is present unavoidable dispersion in view of fabrication thereof in detection characteristics of the two routes of detecting units, there poses a problem in which the measurement accuracy is deteriorated by the dispersion as a matter of fact.
Hence, conventionally, in order to resolve the problem by the two routes of detecting units, there is conceivable a constitution in which there is used one route of a detecting unit using light of light beam having a diameter large enough to cover both of the respective front end portions of the low resolution cantilever portion 1b and the high resolution cantilever portion 1d in place of the two routes of the detecting units.
However, according to the constitution having the one route of a detecting unit, in comparison with the constitution having the two routes of detecting units, there is achieved an advantage of capable of simplifying the constitution, however, in consideration of the fact that the diameter of the light beam is inversely proportional to the measurement accuracy, a deterioration in the measurement accuracy is induced and therefore, the one route of a detecting unit does not necessarily resolve simultaneously all of the above-described problems.
Further, a description has been given such that according to the conventional microprobe 1 and a scanning type probe apparatus using thereof, at each time of measurement, there is needed fine alignment adjustment of respective arrangement positions and angles of the light emitting elements 51 and 52 and the light receiving elements 61 and 62, actually, since the measurement order is an extremely small order of nanometer and accordingly, there also poses a problem in which fine position and angle adjustment needs to be repeated a number of times which requires very troublesome operations for a long period of time.
The invention has been carried out in view of such background and it is an object thereof to provide a microprobe capable of simplifying a constitution thereof, capable of promoting the accuracy of measuring a sample face and capable of dispensing with alignment adjustment each time a measuring operation is performed and a scanning type probe apparatus using the microprobe.
In order to resolve the above-described problem and achieve the object, the present invention includes a low resolution cantilever portion supported by a support portion and integrally formed with heater laminating portions, heater portions formed at the heater laminating portions, piezoresistive elements provided at bending portions and a movable portion having a low resolution stylus and a high resolution cantilever portion supported by the support portion and integrally formed with piezoresistive elements provided at the bending portions and a movable portion having a high resolution stylus.